Electrochemical processing apparatus and method of processing a semiconductor device

ABSTRACT

An electrochemical processing apparatus is provided, in which a substrate and an anode placed in a chamber are partitioned into a cathode region including the substrate and an anode region including the anode by placing a multi-layered structure of a filtration film and a cation exchange film so that the filtration film is positioned on the substrate side. A plating solution containing additives is introduced into the cathode region, whereby a substrate is plated.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electrochemical processing apparatusand a method of processing a semiconductor device.

2. Description of the Related Art

Electrochemical processing is generally used for embedding recesses suchas trenches and through holes formed on or over a semiconductorsubstrate with a metal material such as copper to form wiring and vias.Conventionally, such electrochemical processing has problems thatparticles are generated on an anode side in a plating solution, andadditives such as an accelerator, a leveler, and a suppressor aredecomposed on the anode. In order to prevent such problems, there aresome technologies that an ion exchange film or a filtration filmseparating between an anode and a substrate is used in anelectrochemical processing apparatus.

JP 2003-73889 A describes the configuration in which a chamber ispartitioned into a cathode region and an anode region with an anionexchange film when copper is electro-plated on or over a semiconductorwafer. This configuration is considered to be capable of preventingparticles from adhering to the semiconductor wafer.

JP 2005-133187 A describes a plating technique that an ion exchange filmand a surface of a substrate to be plated are brought close or contactedwith each other and moved relatively. Since plating on an upper portionof a wiring pattern is suppressed to be low plating speed, this isconsidered to be capable of forming a flat electro-plated film.

JP 2000-192298 A describes the configuration in which a partition filmmade of a porous filtration film or a cation exchange film is placedbetween anode electrode plate and a substrate to be plated, whereby achamber body is partitioned into an anode chamber and a cathode chamber.This prevents additives in a plating solution from coming into contactwith the surface of an anode electrode plate to be decomposed, therebysuppressing a plated surface from becoming coarse due to the shortage ofadditives, and can remove oxygen gas generated on the surface of theanode electrode plate rapidly, thereby forming an uniform metalelectro-plated film.

JP 2001-49498 A describes the configuration in which a substrate to beplated and an anode electrode are partitioned by placing an ion exchangeresin or a porous filtration film therebetween. This configuration isconsidered to be capable of preventing air bubbles from adhering to aplated surface of the substrate to be plated.

However, the inventors of the present invention found that there are thefollowing problems in performing plating with the use of thesetechniques.

A cation exchange film that selectively transmits only cations isgenerally composed of a sulfonic group or the like, and the surfacethereof is negatively charged. Therefore, in the case where a cationexchange film is provided between an anode and a substrate, whenadditives are neutral or negatively charged, the cation exchange filmcan suppress the additives from being transmitted. However, in the casewhere the additives are positively charged, the additives are likely toadsorb to the cation exchange film. In general, when a leveler ispositively charged, and a cation exchange film is used, the consumptionrate of the leveler becomes high.

Furthermore, in the case where a filtration film is provided between ananode and a substrate, when a filtration diameter of the filtration filmis set to be too minute, the transmission of ions that are required tobe transmitted between an anode side and a substrate side is alsoprevented. Therefore, the filtration diameter cannot be set to be sominute. For example, in the case of using a dissoluble copper anode asan anode, if copper ions do not move smoothly between the anode and thesubstrate, the use efficiency of the copper ions from anode decreases.Therefore, it is necessary to increase the filtration diameter of thefiltration film to such a degree that the copper ions can betransmitted. Therefore, the transmission of the additives with a smallmolecular weight such as an accelerator cannot be suppressed.

In the above-mentioned conventional technique, since only either one ofa cation exchange film or a filtration film (or an anion exchange film)is provided between an anode and a substrate, the consumption ofadditives in a plating solution cannot be reduced. Furthermore, theadditives are transmitted to the anode side, come into contact with theanode to be decomposed, and are accumulated in the plating solution asimpurities, which cause the defects in an electro-plated film.

SUMMARY

According to the present invention, there is provided an electrochemicalprocessing apparatus, including:

a chamber; and

a multi-layered structure including a filtration film and a cationexchange film,

the multi-layered structure being placed between a substrate and ananode that are placed in the chamber so that the filtration film ispositioned on the substrate side and partitioning the chamber into acathode region including the substrate and an anode region including theanode.

According to the present invention, there is provided a method ofprocessing a semiconductor device, including an electrochemicalprocessing step of plating a substrate in a state where a multi-layeredstructure including a filtration film and a cation exchange film isplaced between a substrate and an anode that are placed in a chamber sothat the filtration film is positioned on the substrate side, and thechamber is partitioned into a cathode region including the substrate andan anode region including the anode. A plating solution containingadditives is used in the electrochemical processing step.

Herein, the filtration film can be a nonpolar filtration film having nopolarity. Furthermore, the filtration film can be configured so as tohave a porous structure and suppress the transmission of molecules witha large molecular weight (molecular diameter) by adjusting a holediameter.

With such a configuration, for example, even in the case where aleveler, an accelerator, and a suppressor that are additives are presentin a cathode region, the leveler can be prevented from adsorbing to acation exchange film, and the additives with a small molecular weightcan be prevented from being transmitted to an anode side. This canreduce the consumption of the additives.

The anode (anode electrode plate) can also be composed of, for example,a dissoluble copper anode, or an insoluble anode. In the case where theanode is composed of a copper anode, a multi-layered film can beconfigured so as to transmit copper ions.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, advantages and features of the presentinvention will be more apparent from the following description taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view illustrating a configuration of anelectrochemical processing apparatus of the present invention;

FIG. 2 is a plan view in which a multi-layered structure included in theelectrochemical processing apparatus of the present invention is seenfrom the filtration film side;

FIG. 3 is a view illustrating the consumption of a leveler in anexample;

FIG. 4 is a diagram illustrating the consumption of an accelerator inthe example;

FIG. 5 is a diagram illustrating the consumption of a suppressor in theexample; and

FIGS. 6A and 6B are cross-sectional views illustrating a process of asemiconductor device of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention will be now described herein with reference toillustrative embodiments. Those skilled in the art will recognize thatmany alternative embodiments can be accomplished using the teachings ofthe present invention and that the invention is not limited to theembodiments illustrated for explanatory purposes.

FIG. 1 is a cross-sectional view illustrating a configuration of anelectrochemical processing apparatus 200 in the present embodiment.

The electrochemical processing apparatus 200 includes a chamber 201, andan anode 220 placed in the chamber 201. In the present embodiment, theanode 220 can be composed of a dissoluble copper anode. In the chamber201, a plating solution 202 is contained. The plating solution 202 iscomposed of, for example, copper sulfate aqueous solution. In addition,the electrochemical processing apparatus 200 has a substrate support(not shown) on which a substrate 100 is to be placed, and the substrate100 is placed on the substrate support.

The electrochemical processing apparatus 200 includes a multi-layeredstructure 204 of a filtration film 210 and a cation exchange film 208placed between the substrate 100 and the anode 220. The multi-layeredstructure 204 is placed so that the filtration film 210 is positioned onthe substrate 100 side. The chamber 201 is partitioned into a cathoderegion 202 a including the substrate 100 and an anode region 202 bincluding the anode 220 by the multi-layered structure 204. Furthermore,the electrochemical processing apparatus 200 includes a diffusion plate214 placed between the multi-layered structure 204 and the substrate100. The diffusion plate 214 is placed for the purpose of making theflow of the plating solution 202 uniform in the vicinity of thesubstrate 100. It should be noted that the diffusion plate 214 isconfigured so as to have a sufficiently large hole diameter and totransmit components of the plating solution 202.

In the cathode region 202 a, levelers, accelerators, and suppressors areintroduced as additives into the plating solution 202.

In the present embodiment, as the levelers, for example, a positivelycharged material having a molecular weight of 2000 to 3000 can be used.As such a material, for example, a cationic amine polymer can be used.

In the present embodiment, as the accelerators, for example, anegatively charged material having a molecular weight of 500 or less anda disulfide bond can be used. As such a material, the one represented bythe general formula: SO₃—R₁—S—S—R₂—SO₃— (herein, R₁ and R₂ arerespectively hydrocarbon chains independently) can be used.

In the present embodiment, as the suppressors, for example, a materialhaving a molecular weight of 2000 to 3000 and no polarity can be used.As such a material, for example, polyethylene glycol can be used.

The multi-layered structure 204 is configured so as to suppress thetransmission of levelers, accelerators, and suppressors. Furthermore, inthe present embodiment, the multi-layered structure 204 is configured soas to transmit copper ions. The filtration film 210 has minute holes,and transmits molecules with a size smaller than the hole diameter andsuppresses the transmission of molecules with a size larger than thehole diameter. The filtration film 210 is configured so as to have nopolarity and have a hole diameter of suppressing the transmission of atleast the levelers. In the present embodiment, the hole diameter of thefiltration film 210 can be set to be 0.5 μm or less. This can suppressthe transmission of the levelers. On the other hand, in order totransmit copper ions, the hole diameter of the filtration film 210 canbe set to be 0.01 μm or more. As the filtration film 210, for example,polypropylene can be used.

The cation exchange film 208 selectively transmits only cations. As thecation exchange film 208, for example, polyacrylic resin having asulfonic group can be used.

In the present embodiment, the multi-layered structure 204 includes amulti-layered film 206 in which the filtration film 210 and the cationexchange film 208 are provided in contact with each other, and a supportplate 212 supporting the multi-layered film 206. By using themulti-layered film 206, bubbles of air or the like can be prevented fromentering between the filtration film 210 and the cation exchange film208, and the flow of the plating solution in the chamber 201 can beregulated easily.

FIG. 2 is a plan view in which the multi-layered structure 204 is seenfrom the filtration film 210 side. The chamber 201 is configured in acylindrical shape (not shown). The multi-layered structure 204 isconfigured in a size equal to that of the cross-section of the chamber201, and partitions the chamber 201 into the cathode region 202 a andthe anode region 202 b. The multi-layered structure 204 can have anyconfiguration as long as levelers, accelerators, and suppressorsintroduced in the cathode region 202 a are not transmitted to the anoderegion 202 b. As other examples, a partition wall that partiallypartitions the plating solution 202 and the substrate 100 is provided,and the multi-layered structure 204 may be placed in an open portionwhich is not partitioned by the partition wall. Herein, the supportplate 212 is composed of, for example, a plastic material, and has aframework reinforcing the multi-layered film 206.

Next, the function of the multi-layered structure 204 configured asdescribed above will be described.

In the multi-layered structure 204, the filtration film 210 is providedon the cathode region 202 a side. Therefore, in the case where levelers,accelerators, and suppressors are introduced in the cathode region 202a, first, the transmission of levelers and suppressors having a largemolecular weight are suppressed by the filtration film 210. This canprevent levelers and suppressors from moving to the anode region 202 b,thereby reducing the consumption thereof. Furthermore, the positivelycharged levelers can be prevented from coming into contact with thecation exchange film 208, so the consumption of levelers can be reducedmore. On the other hand, even when accelerators having a small molecularweight are transmitted through the filtration film 210, the cationexchange film 208 can prevent accelerators from moving to the anoderegion 202 b. Consequently, even when the hole diameter of thefiltration film 210 is set in such a degree as to transmit accelerators,the consumption of accelerators can be reduced.

Next, the procedure of processing a semiconductor device using theelectrochemical processing apparatus 200 in the present embodiment willbe described with reference to FIG. 6. A semiconductor device 300 isformed on a semiconductor substrate 302, including transistors and thelike, an insulating film 304 formed over the transistors, and aninsulating film 306 formed over the insulating film 304. Wiring and viasare formed in the insulating films 304 and 306.

In the semiconductor device 300 thus configured, interconnect features(trenches) are formed on the insulating film 306. Herein, as shown, inthe insulating film 306, interconnect feature 308, interconnect feature310, interconnect feature 312, interconnect feature 314, interconnectfeature 316, interconnect feature 318, and interconnect feature 320 areformed (FIG. 6A).

The procedure of burying such trenches with a wiring material will beshown below. First, a barrier metal film is formed in the trenches ofthe insulating film 306. TaN/Ta is usually used as a barrier metal ofcopper interconnects. Then a seed film for plating is formed on thebarrier film. Herein, a seed film is made of a copper film formed by CVDor the like.

Then, the substrate with the seed film formed thereon is plated usingthe electrochemical processing apparatus 200. Consequently, anelectro-plated film 332 is formed in the trenches. Herein, theelectro-plated film 332 is, for example, made of a copper film (FIG.6B). The defects caused by a decomposition product of the additives aresuppressed by using the electrochemical processing apparatus 200 in thepresent embodiment.

EXAMPLE

In the same way as in the configuration of the apparatus illustrated inFIG. 1, using an apparatus in which the multi-layered structure 204 isplaced between the substrate 100 and the anode 220 (in theelectrochemical processing apparatus), the consumption of a leveler, aaccelerator, and a suppressor during plating were checked, respectively.A cation amine polymer with a molecular weight of 2500 was used as theleveler, bis(3-sulfopropyl) disulfide with a molecular weight of 310 wasused as the accelerator, and polyethylene glycol with a molecular weightof 2200 was used as the suppressor. As the cation exchange film,polyacrylic resin having a sulfonic group was used, and as thefiltration film, polypropylene was used. An experiment was conductedevery day for 30 days. For comparison, the consumption of the leveler,the accelerator, and the suppressor were respectively checked in thecase of only the filtration film, only the cation exchange film, and theabsence of the filtration film and the cation exchange film.

FIGS. 3 to 5 illustrate the results. The conditions are as follows.

(1) Multi-layered structure (filtration film+cation exchange film:multi-layered structure 204)

(2) Only filtration film (3) Only cation exchange film (4) Absence offiltration film and cation exchange film

FIG. 3 illustrates the consumption of the leveler. Herein, the verticalaxis represents the consumption of the leveler normalized with the case(1) using the multi-layered structure being 1. In any of the cases (1)to (3), the consumption of the leveler was reduced compared with thecase (4) without using a film. However, in the case (3) using only thecation exchange film, the consumption of the leveler was increased abouttwice that of the case (1) using the multi-layered film. In the case (2)using only the filtration film, the consumption of the leveler wasincreased slightly compared with the case (1) using the multi-layeredfilm; however, no large change was found. In any case, there was nochange in film characteristics even after the elapse of 30 days.

FIG. 4 illustrates the consumption of the accelerator. Herein, thevertical axis represents the consumption of the accelerator normalizedwith the case (1) using the multi-layered film being 1. In any of thecases (1) to (3), the consumption of the accelerator was reducedcompared with the case (4) without using a film. However, in the case(2) using only the filtration film, the consumption of the acceleratorwas increased by about 1.5 times that of the case (1) using themulti-layered film. In the case (3) using only the cation exchange film,the consumption of the accelerator was increased slightly compared withthe case (1) using the multi-layered film; however, no large change wasfound. In any case, there was no change in film characteristics evenafter the elapse of 30 days.

FIG. 5 illustrates the consumption of the suppressor. Herein thevertical axis represents the consumption of the suppressor normalizedwith the case (1) using the multi-layered film being 1. In any of thecases (1) to (3), the consumption of the suppressor was reduced comparedwith the case (4) without using a film. In the case (2) using only thefiltration film and the case (3) using only the cation exchange film,the consumption of the accelerator was increased slightly compared withthe case (1) using the multi-layered film; however, no large change wasfound. In any of the cases, there was no change in film characteristicseven after the elapse of 30 days.

As described above, by using the multi-layered structure 204, theconsumption of all the three additives: the leveler, the accelerator,and the suppressor were reduced simultaneously.

The embodiment of the present invention has been described withreference to the drawings. However, it is represented merely for anillustrative purpose, and other various configurations can also beadopted.

In the embodiment, the case where the anode 220 is a copper anode hasbeen illustrated. However, as the anode 220, an insoluble anode may beused. Even in this case, the multi-layered structure 204 can beconfigured in the same way as in the above; however, it may beconfigured so as not to transmit copper ions, for example.

Furthermore, in the above-mentioned embodiment, copper plating has beenillustrated, in which the plating solution contains copper ions.However, the present invention can be applied to other various plating.For example, the present invention can be applied to the plating inwhich bumps of a semiconductor device are formed using nickel or thelike. Even in this case, as an anode, any of a dissoluble or insolubleanode may be used.

1. An electrochemical processing apparatus, comprising: a chamber; and amulti-layered structure provided to partition the chamber into an anoderegion and a cathode region, said structure including a filtration filmfacing said cathode region and a cation exchange film facing said anoderegion.
 2. The apparatus according to claim 1, wherein the filtrationfilm and the cation exchange film are provided in contact with eachother.
 3. The apparatus according to claim 1, wherein the filtrationfilm has a hole diameter of 0.5 μm or less.
 4. The apparatus accordingto claim 1, wherein: the chamber has a plating solution containing aleveler, an accelerator, and a suppressor introduced into the cathoderegion; and the multi-layered structure is configured to suppresstransmission of the accelerator, the leveler, and the suppressor.
 5. Theapparatus according to claim 1, wherein the anode is made of copper. 6.The apparatus according to claim 5, wherein the multi-layered structureis configured to allow transmission of copper ions.
 7. A chamberincluding an anode and a cathode, a filtration film provided in thechamber between the anode and the cathode, and a cation exchange filmprovided in the chamber between the
 8. The chamber according to claim 7,the cathode is a filtration film and the anode. semiconductor wafer. 9.A method of plating a conductive film by use of an electrochemicalprocessing apparatus which includes a chamber with an anode, a cathode,a filtration film between the anode and the cathode and a cationexchange film between the filtration film and the anode, the methodcomprising plating a semiconductor substrate into the chamber as thecathode, applying an electric power between the anode and thesemiconductor substrate to plate a conductive film on the semiconductorsubstrate.
 10. The method according to claim 9, further comprisingintroducing a plating solution containing a leveler, an accelerator, anda suppressor into the chamber.
 11. The method according to claim 10,wherein the anode comprising a copper so that a copper film is plated onthe semiconductor substrate.